화간 : sin(2α+α) / sin α-2cos(α+α). RT.

화간 : sin(2α+α) / sin α-2cos(α+α). RT.

원식= [sin(α+α)cosα+cos(α+α)sinα- 2sinαcos(알파+α) ] /sinα = [sin(α+α)cosα - cos(알파+α)sinα]/sina=sinα/sinα